A geophysical foundation for alternative farm policy

Reorientation of aquaculture production systems can reduce environmental impacts and improve nutrition security in Bangladesh

Aquatic foods are a critical source of human nutrition in many developing countries. As a result, declines in wild-caught fish landings threaten nutritionally vulnerable populations. Aquaculture presents an opportunity to meet local demand, but it also places pressure on natural resource inputs and causes a range of environmental impacts. Here, we examine whether current aquaculture systems in Bangladesh can be reoriented to address prevailing nutritional deficiencies while minimizing these environmental impacts. Current fish farming practices, even when optimized, cannot fully supply the same essential micronutrient densities of zinc, iron and calcium as wild-caught fish. However, when the proportion of highly nutrient-dense small indigenous fish species (SIS) was increased to at least 30% of the total output in any of the 14 aquaculture production systems analysed, these systems were able to meet or surpass the nutrient densities of average wild-capture fisheries. Extensive aquaculture systems that co-produce fish and rice had the lowest environmental burdens in six out of seven metrics examined when the composition of all aquaculture systems was modified to include 50% SIS. Nutrition-sensitive aquaculture that provides greater human health benefits and minimizes environmental impacts is a key societal challenge that requires targeted interventions and supportive policies.

Environmentally Optimal, Nutritionally Sound, Protein and Energy Conserving Plant Based Alternatives to U.S. Meat

Because meat is more resource intensive than vegetal protein sources, replacing it with efficient plant alternatives is potentially desirable, provided these alternatives prove nutritionally sound. We show that protein conserving plant alternatives to meat that rigorously satisfy key nutritional constraints while minimizing cropland, nitrogen fertilizer (Nr) and water use and greenhouse gas (GHG) emissions exist, and could improve public health. We develop a new methodology for identifying nutritional constraints whose satisfaction by plant eaters is challenging, disproportionately shaping the optimal diets, singling out energy, mass, monounsaturated fatty acids, vitamins B_3,6,12 and D, choline, zinc, and selenium. By replacing meat with the devised plant alternatives—dominated by tofu, soybeans, peanuts, and lentils—Americans can collectively eliminate pastureland use while saving 35–50% of their diet related needs for cropland, Nr, and GHG emission, but increase their diet related irrigation needs by 15%. While widely replacing meat with plants is logistically and culturally challenging, few competing options offer comparable multidimensional resource use reduction.

A model for 'sustainable' US beef production

Food production dominates land, water and fertilizer use and is a greenhouse gas source. In the United States, beef production is the main agricultural resource user overall, as well as per kcal or g of protein. Here, we offer a possible, non-unique, definition of 'sustainable' beef as that subsisting exclusively on grass and by-products, and quantify its expected US production as a function of pastureland use. Assuming today's pastureland characteristics, all of the pastureland that US beef currently use can sustainably deliver ≈45% of current production. Rewilding this pastureland's less productive half (≈135 million ha) can still deliver ≈43% of current beef production. In all considered scenarios, the ≈32 million ha of high-quality cropland that beef currently use are reallocated for plant-based food production. These plant items deliver 2- to 20-fold more calories and protein than the replaced beef and increase the delivery of protective nutrients, but deliver no B₁₂. Increased deployment of rapid rotational grazing or grassland multi-purposing may increase beef production capacity.

Land, irrigation water, greenhouse gas, and reactive nitrogen burdens of meat, eggs, and dairy production in the United States

Livestock production impacts air and water quality, ocean health, and greenhouse gas (GHG) emissions on regional to global scales and it is the largest use of land globally. Quantifying the environmental impacts of the various livestock categories, mostly arising from feed production, is thus a grand challenge of sustainability science. Here, we quantify land, irrigation water, and reactive nitrogen (Nr) impacts due to feed production, and recast published full life cycle GHG emission estimates, for each of the major animal-based categories in the US diet. Our calculations reveal that the environmental costs per consumed calorie of dairy, poultry, pork, and eggs are mutually comparable (to within a factor of 2), but strikingly lower than the impacts of beef. Beef production requires 28, 11, 5, and 6 times more land, irrigation water, GHG, and Nr, respectively, than the average of the other livestock categories. Preliminary analysis of three staple plant foods shows two- to sixfold lower land, GHG, and Nr requirements than those of the nonbeef animal-derived calories, whereas irrigation requirements are comparable. Our analysis is based on the best data currently available, but follow-up studies are necessary to improve parameter estimates and fill remaining knowledge gaps. Data imperfections notwithstanding, the key conclusion--that beef production demands about 1 order of magnitude more resources than alternative livestock categories--is robust under existing uncertainties. The study thus elucidates the multiple environmental benefits of potential, easy-to-implement dietary changes, and highlights the uniquely high resource demands of beef.

Effect of localizing fruit and vegetable consumption on greenhouse gas emissions and nutrition, Santa Barbara County

The US agrifood system is very productive, but highly centralized and resource intensive with very weak links between production and consumption. This contributes to high levels of malnutrition and greenhouse gas emissions (GHGE). A popular approach to improvement is localization-reducing direct transport (farm to retail distance, or "food miles"). We examined Santa Barbara County (SBC) California, which mirrors the high production, nutritional and environmental problems, and growing localization movement of California. SBC ranks in the top 1% of US counties in value of agricultural products, and >80% of this value is produce (fruits and vegetables). We calculated the amount of produce grown in and consumed in SBC and estimated that >99% of produce grown in SBC is exported from the county, and >95% of produce consumed in SBC is imported. If all produce consumed in SBC was grown in the county (100% localization), it would reduce GHGE from the agrifood system <1%, and not necessarily affect nutrition. While food miles capture only a portion of the environmental impact of agrifood systems, localization could be done in ways that promote synergies between improving nutrition and reducing GHGE, and many such efforts exist in SBC.